I/O Options EntryUsed to request output of modal effective mass, modal participation factors, and modal effective mass fractions in Normal Modes Analysis.


MEFFMASS (type, format, GRID=gid, output) = option




Argument Options Description
type <COMP, PROP, SET=ID, blank>
Output is available based on the HyperMesh component in an .effmass file file. 8
Output is available based on the property in an .effmass file. 8
Output is available based on the HyperMesh set name in an .effmass file. 8
ID denotes the identification of an MEFFSET entry.
MEFFSET groups element set IDs based on which output is desired.
Blank (Default)
Output is available for the entire model in the .out file. In this case, an .effmass file is not created.
format <PUNCH, NOPUNCH, OPTI, HG, blank>
The MEFFMASS output is printed to the PUNCH file and the .out file.
The PUNCH file output is only activated if OUTPUT,PUNCH is specified.
The MEFFMASS output is printed to the .out file. and not to the PUNCH file.
The MEFFMASS output is printed to the an .effmass ASCII file and the .out file.
The MEFFMASS output is available in a HyperGraph presentation format file (_mass.mvw) and the .out file.
Blank (Default)
The MEFFMASS output is printed only to the .out file.
gid <Grid ID>
Grid ID
The grid point reference for the calculation of the rigid body mass matrix.
Blank (Default)
The grid point reference for the rigid body mass matrix calculation is the basic coordinate system.
output <SUMMARY, PARTFAC, MEFFM, MEFFW, FRACSUM, ALL> Requests output of:
SUMMARY (Default)
Modal Effective Mass matrix, Modal Effective Mass fraction, and the Rigid Body Mass matrix.
Modal Participation Factors.
Modal Effective Mass matrix in units of mass.
Modal Effective Mass matrix in units of weight.
In addition, Modal Effective Mass matrix in units of mass is also printed. 4
Modal Effective Mass fraction.
All matrices are output. They are: Rigid Body Mass Matrix, Modal Participation Factors, Modal Participation Factor Ratios, Modal Effective Mass, Modal Effective Mass (in weight units), and Modal Effective Mass fraction matrices.
option <YES,NO>
YES (Default)
The matrix output is printed based on the options specified.
The matrix output is not printed.


  1. Output from MEFFMASS is only supported for Normal Modes Analysis.
  2. PARAM,EFFMAS,YES is also available for similar outputs of the specified matrices above for Normal Modes Analysis. PARAM,EFFMAS,YES does not provide the output for Rigid Body Mass matrix, Modal Effective Mass matrix in weight units, or grid-based selection.
  3. Compared to PARAM,EFFMASS,YES, the MEFFMASS I/O Options Entry provides additional output control and can be used in place of PARAM,EFFMASS,YES if the output is to be fine-tuned or desired only for particular grids.
  4. With the MEFFW option, the modal effective mass is divided by PARAM,WTMASS.
  5. Multiple subcases can have their own MEFFMASS definitions.
  6. The following example demonstrates usage of the SET = ID option along with MEFFSET. In this case, output is available for each HyperMesh set name (‘set01’, ‘set02’ and so on).
    . . .
    +,102, 103, 104
    $HMSET      101       11 "set01" 18
    $HMSETTYPE       101 "regular" 18
    SET     101     ELEM    PROP    
    +       1
    $HMSET      102       11 "set02" 18
    $HMSETTYPE       102 "regular" 18
    SET     102     ELEM    PROP    
    +       2
    $HMSET      103       11 "set03" 18
    $HMSETTYPE       103 "regular" 18
    SET     103     ELEM    PROP    
    +       3
    . . .
  7. When SET = ID is used, the output header for each set uses the HyperMesh set name by default. When the set name is not specified in the input file, the set ID is specified.
  8. If multiple types are specified in the same MEFFMASS entry, the last one will be used. For example, if MEFFMASS (COMP, PROP, SET = 101) is specified, then type of SET = ID will be used.
  9. For detailed information regarding how the matrices are calculated, refer to PARAM, EFFMAS.